The hydraulic trim-tilt system disclosed in U.S. Pat. No. 4,391,592 and No. 4,490,120, both to Hundertmark, provide trim-tilt systems for outboard propulsion units which use a pilot valve and a trim piston to provide different operating pressures for the tilt and trim ranges of operation. The prior systems would allow the trim angle to be changed under power but prevented the engine from being tilted above the trim range while under power. These systems would also prevent operation of the motor in a shallow water tilt mode, that is, at a tilt angle above the normal trim range but with the propeller still in the water. This shallow water operation is occasionally desirable when operating in shallow water or beaching a boat. The prior device could be raised to the shallow water tilt range by cutting the power and raising the motor to the desired tilt angle, but the propulsion unit would rapidly tilt down if engine power was applied.